"nosql" entries

Crowdsourcing Isn’t Broken — great rundown of ways to keep crowdsourcing on track. As with open sourcing something, just throwing open the doors and hoping for the best has a low probability of success.

etcd Hits 2.0 — first major stable release of an open source, distributed, consistent key-value store for shared configuration, service discovery, and scheduler coordination.

You Can’t Play 20 Questions With Nature and Win (PDF) — There is, I submit, a view of the scientific endeavor that is implicit (and sometimes explicit) in the picture I have presented above. Science advances by playing 20 questions with nature. The proper tactic is to frame a general question, hopefully binary, that can be attacked experimentally. Having settled that bits-worth, one can proceed to the next. The policy appears optimal – one never risks much, there is feedback from nature at every step, and progress is inevitable. Unfortunately, the questions never seem to be really answered, the strategy does not seem to work. An old paper, but still resonant today. (via Mind Hacks)

How NoSQL databases scale vertically and horizontally, and what you should consider when building a DB cluster.

As product manager for Bigstep’s Full Metal Cloud, I work with a lot of amazing technologies. Most of my work actually involves pushing applications to their limits. My mission is simple: make sure we get the highest performance possible out of each setup we test, then use that knowledge to constantly improve our services.

Here are some of the things I’ve learned along the way about how NoSQL databases scale vertically and horizontally, and what things you should consider when building a DB cluster. Some of these findings can be applied to RDBMS as well, so read on even if you’re still a devoted SQL fan. You might just get up to 60% more performance out of that database soon enough. Read more…

High-performing memory throws many traditional decisions overboard

Over the past decade, SSD drives (popularly known as Flash) have radically changed computing at both the consumer level — where USB sticks have effectively replaced CDs for transporting files — and the server level, where it offers a price/performance ratio radically different from both RAM and disk drives. But databases have just started to catch up during the past few years. Most still depend on internal data structures and storage management fine-tuned for spinning disks.

Citing price and performance, one author advised a wide range of database vendors to move to Flash. Certainly, a database administrator can speed up old databases just by swapping out disk drives and inserting Flash, but doing so captures just a sliver of the potential performance improvement promised by Flash. For this article, I asked several database experts — including representatives of Aerospike, Cassandra, FoundationDB, RethinkDB, and Tokutek — how Flash changes the design of storage engines for databases. The various ways these companies have responded to its promise in their database designs are instructive to readers designing applications and looking for the best storage solutions.

Machine Learning Done Wrong — [M]ost practitioners pick the modeling algorithm they are most familiar with rather than pick the one which best suits the data. In this post, I would like to share some common mistakes (the don’t-s).

Bandits for Recommendations — A common problem for internet-based companies is: which piece of content should we display? Google has this problem (which ad to show), Facebook has this problem (which friend’s post to show), and RichRelevance has this problem (which product recommendation to show). Many of the promising solutions come from the study of the multi-armed bandit problem.

Droplets — the Droplet is almost spherical, can self-right after being poured out of a bucket, and has the hardware capabilities to organize into complex shapes with its neighbors due to accurate range and bearing. Droplets are available open-source and use cheap vibration motors and a 3D printed shell. (via Robohub)

Apple’s App Store Approval Guidelines — some of the plainest English I’ve seen, especially the Introduction. I can only aspire to that clarity. If your App looks like it was cobbled together in a few days, or you’re trying to get your first practice App into the store to impress your friends, please brace yourself for rejection. We have lots of serious developers who don’t want their quality Apps to be surrounded by amateur hour.

Cockroach — a distributed key/value datastore which supports ACID transactional semantics and versioned values as first-class features. The primary design goal is global consistency and survivability, hence the name. Cockroach aims to tolerate disk, machine, rack, and even datacenter failures with minimal latency disruption and no manual intervention. Cockroach nodes are symmetric; a design goal is one binary with minimal configuration and no required auxiliary services.

Linux Foundation Providing for Core Infrastructure Projects — press release, but interested in how they’re tackling sustainability—they’re taking on identifying worthies (glad I’m not the one who says “you’re not worthy” to a project) and being the non-profit conduit for the dosh. Interesting: implies they think the reason companies weren’t supporting necessary open source projects was some combination of being unsure who to support (projects you use, surely?) and how to get them money (ask?). (Sustainability of open source projects is a pet interest of mine)

Insecure Hardware, Doc Database, Kids Programming, and Ad-Blocking AP

Researchers Can Slip an Undetectable Trojan into Intel’s Ivy Bridge CPUs (Ars Technica) — The exploit works by severely reducing the amount of entropy the RNG normally uses, from 128 bits to 32 bits. The hack is similar to stacking a deck of cards during a game of Bridge. Keys generated with an altered chip would be so predictable an adversary could guess them with little time or effort required. The severely weakened RNG isn’t detected by any of the “Built-In Self-Tests” required for the P800-90 and FIPS 140-2 compliance certifications mandated by the National Institute of Standards and Technology.

No Managers — If we could find a way to replace the function of the managers and focus everyone on actually producing for our Students (customers) then it would actually be possible to be a #NoManager company. In my future posts I’ll explain how we’re doing this at Treehouse.

The 20 Smartest Things Jeff Bezos Has Ever Said (Motley Fool) — I feel like the 219th smartest thing Jeff Bezos has ever said is still smarter than the smartest thing most business commentators will ever say. (He says, self-referentially) “Invention requires a long-term willingness to be misunderstood.”

The Truth of Fact, The Truth of Feeling (Ted Chiang) — story about what happens when lifelogs become searchable. Now with Remem, finding the exact moment has become easy, and lifelogs that previously lay all but ignored are now being scrutinized as if they were crime scenes, thickly strewn with evidence for use in domestic squabbles. (via BoingBoing)

Retreading old topics can be a powerful source of epiphany, sometimes more so than simple extra-box thinking. I was a computer science student, of course I knew statistics. But my recent years as a NoSQL (or better stated: distributed systems) junkie have irreparably colored my worldview, filtering every metaphor with a tinge of information management.

Lounging on a half-world plane ride has its benefits, namely, the opportunity to read. Most of my Delta flight from Tel Aviv back home to Portland lacked both wifi and (in my case) a workable laptop power source. So instead, I devoured Nate Silver’s book, The Signal and the Noise. When Nate reintroduced me to the concept of statistical overfit, and relatedly underfit, I could not help but consider these cases in light of the modern problem of distributed data management, namely, operators (you may call these operators DBAs, but please, not to their faces).

When collecting information, be it for a psychological profile of chimp mating rituals, or plotting datapoints in search of the Higgs Boson, the ultimate goal is to find some sort of usable signal, some trend in the data. Not every point is useful, and in fact, any individual could be downright abnormal. This is why we need several points to spot a trend. The world rarely gives us anything clearer than a jumble of anecdotes. But plotted together, occasionally a pattern emerges. This pattern, if repeatable and useful for prediction, becomes a working theory. This is science, and is generally considered a good method for making decisions.

On the other hand, when lacking experience, we tend to over value the experience of others when we assume they have more. This works in straightforward cases, like learning to cook a burger (watch someone make one, copy their process). This isn’t so useful as similarities diverge. Watching someone make a cake won’t tell you much about the process of crafting a burger. Folks like to call this cargo cult behavior.

How Fit are You, Bro?

You need to extract useful information from experience (which I’ll use the math-y sounding word datapoints). Having a collection of datapoints to choose from is useful, but that’s only one part of the process of decision-making. I’m not speaking of a necessarily formal process here, but in the case of database operators, merely a collection of experience. Reality tends to be fairly biased toward facts (despite the desire of many people for this to not be the case). Given enough experience, especially if that experience is factual, we tend to make better and better decisions more inline with reality. That’s pretty much the essence of prediction. Our mushy human brains are more-or-less good at that, at least, better than other animals. It’s why we have computers and Everybody Loves Raymond, and my cat pees in a box.

Imagine you have a sufficient amount of relevant datapoints that you can plot on a chart. Assuming the axes have any relation to each other, and the data is sound, a trend may emerge, such as a line, or some other bounding shape. A signal is relevant data that corresponds to the rules we discover by best fit. Noise is everything else. It’s somewhat circular sounding logic, and it’s really hard to know what is really a signal. This is why science is hard, and so is choosing a proper database. We’re always checking our assumptions, and one solid counter signal can really be disastrous for a model. We may have been wrong all along, missing only enough data. As Einstein famously said in response to the book 100 Authors Against Einstein: “If I were wrong, then one would have been enough!”

Database operators (and programmers forced to play this role) must make predictions all the time, against a seemingly endless series of questions. How much data can I handle? What kind of latency can I expect? How many servers will I need, and how much work to manage them?

So, like all decision making processes, we refer to experience. The problem is, as our industry demands increasing scale, very few people actually have much experience managing giant scale systems. We tend to draw our assumptions from our limited, or biased smaller scale experience, and extrapolate outward. The theories we then tend to concoct are not the optimal fit that we desire, but instead tend to be overfit.

Overfit is when we have a limited amount of data, and overstate its general implications. If we imagine a plot of likely failure scenarios against a limited number of servers, we may be tempted to believe our biggest odds of failure are insufficient RAM, or disk failure. After all, my network has never given me problems, but I sure have lost a hard drive or two. We take these assumptions, which are only somewhat relevant to the realities of scalable systems and divine some rules for ourselves that entirely miss the point.

In a real distributed system, network issues tend to consume most of our interest. Single-server consistency is a solved problem, and most (worthwhile) distributed databases have some sense of built in redundancy (usually replication, the root of all distributed evil).Read more…